We're doing all we can for Thorne: Carr

Foreign Minister Bob Carr says the government is doing all it can to help a young West Australian man imprisoned for terrorist offences in Saudi Arabia.

Senator Carr has defended his department against claims it's done nothing to help Shayden Thorne, 25, pointing to more than 50 representations and six visits by embassy officials over 18 months.

"We do our best for Australians who are in trouble overseas," he told reporters in Sydney on Thursday.

"But if you're in trouble overseas, you're in trouble in a different jurisdiction, and Australian law does not apply.

"Shayden Thorne has chosen to live in Saudi Arabia. He's lived there for 12 years and the laws of Saudi Arabia apply to him."

Thorne has been in custody since November 2011. His younger brother Junaid is in hiding in the country, apparently wanted by authorities for questioning after having previously been detained for two months.

The boys are Aboriginal and are Australian citizens but moved to Saudi Arabia with their father.